Rotation of a driveshaft at or near a resonating frequency of the driveshaft may lead to an undesired vibration of the driveshaft. Further, rotation of a driveshaft which is unbalanced may also lead to the undesired vibration of the driveshaft, resulting in customer dissatisfaction. Rotation of the driveshaft with the undesired vibration, regardless of its source, may also lead to excessive wear of a plurality of components of the driveshaft. Center bearings, shaft end components (such as yokes), universal joint crosses, needle bearings, and a tubular portion of the driveshaft may all be excessively worn by the undesired vibration of the driveshaft.
Typically, as a length of the driveshaft increases, the resonating frequency decreases. In vehicles having long lengths of driveshaft between a vehicle powertrain and a drive axle, such as commercial trucks, the resonating frequency of the driveshaft may approach an operational speed of the driveshaft. To relieve the undesired vibration, the driveshaft may comprise a plurality of sections joined by joints. Unfortunately, adding joints to the driveshaft greatly increases a cost and a weight of the driveshaft, and thus a vehicle the driveshaft is incorporated in.
Alternately, to relieve the undesired vibration, the diameter of the driveshaft, and thus a diameter of the shaft end components, may be increased. However, increasing the diameter of the driveshaft and the diameter of the shaft end components also greatly increases the cost of the driveshaft, and thus the vehicle the driveshaft is incorporated in.
Following manufacture of the driveshaft but prior to installation of the driveshaft in the vehicle, the driveshaft is typically balanced. Through the use of a dynamic balancing machine, a mass and a location of a balancing weight on the driveshaft is determined. After application of the balancing weight, the driveshaft is substantially balanced, reducing the undesired vibration of the driveshaft during operation. However, balancing of the driveshaft increases a time of manufacture of the driveshaft and therefore increases the cost of the driveshaft, and thus the vehicle the driveshaft is incorporated in.
The driveshaft formed from aluminum reduces the weight of the driveshaft. Where formed using a hydroforming process, the driveshaft has an increased resonating frequency and a decreased manufacturing cost. Consequently, the driveshaft formed from aluminum using the hydroforming process is advantageous over the driveshaft formed from a steel using the hydroforming process. However, conventional methods used to hydroform driveshafts as applied to aluminum have been unsuccessful, as a maximum strain limit for forming aluminum is less than a maximum strain limit for forming steel.
It would be advantageous to develop a driveshaft that may be formed using a hydroforming process, reduces a cost of the driveshaft, and has an increased critical speed.